+#define hex(a) (hexchar[(a) & 15])
+static void write_size_header(char *buf, int n)
+{
+ static char hexchar[] = "0123456789abcdef";
+
+ buf[0] = hex(n >> 12);
+ buf[1] = hex(n >> 8);
+ buf[2] = hex(n >> 4);
+ buf[3] = hex(n);
+ buf[4] = ' ';
+}
+
+int read_size_header(const char *buf)
+{
+ int i, len = 0;
+
+ for (i = 0; i < 4; i++) {
+ unsigned char c = buf[i];
+ len <<= 4;
+ if (c >= '0' && c <= '9') {
+ len += c - '0';
+ continue;
+ }
+ if (c >= 'a' && c <= 'f') {
+ len += c - 'a' + 10;
+ continue;
+ }
+ return -E_SIZE_PREFIX;
+ }
+ if (buf[4] != ' ')
+ return -E_SIZE_PREFIX;
+ return len;
+}
+